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proc/softirqs: replace seq_printf with seq_put_decimal_ull_width

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seq_printf is costy, on a system with n CPUs, reading /proc/softirqs
would yield 10*n decimal values, and the extra cost parsing format string
grows linearly with number of cpus. Replace seq_printf with
seq_put_decimal_ull_width have significant performance improvement.
On an 8CPUs system, reading /proc/softirqs show ~40% performance
gain with this patch.

Signed-off-by: David Wang <00107082@163.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Wang 2024-11-06 10:12:28 +08:00 committed by Linus Torvalds
parent ff7afaeca1
commit 84b9749a3a
1 changed files with 1 additions and 1 deletions
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fs/proc/softirqs.c
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@ -20,7 +20,7 @@ static int show_softirqs(struct seq_file *p, void *v)
for (i = 0; i < NR_SOFTIRQS; i++) { for (i = 0; i < NR_SOFTIRQS; i++) {
seq_printf(p, "%12s:", softirq_to_name[i]); seq_printf(p, "%12s:", softirq_to_name[i]);
for_each_possible_cpu(j) for_each_possible_cpu(j)
seq_printf(p, " %10u", kstat_softirqs_cpu(i, j)); seq_put_decimal_ull_width(p, " ", kstat_softirqs_cpu(i, j), 10);
seq_putc(p, '\n'); seq_putc(p, '\n');
} }
return 0; return 0;